The discovery of graphene in 2004 has sparked enormous scientific interest. This interest is largely due to the very interesting properties of graphene, which include an extremely large surface area (˜2630 m2g−1), high intrinsic mobility (˜200,000 cm2 V−1 s−1), high Young's modulus (˜1 TPa), thermal conductivity (˜5,000 μm−1 K−1), and optical transmittance (˜97.7%).
This suite of properties is superior to those observed for carbon nanotubes. In the case of carbon nanotubes, similar interest was generated when they were first discovered. The dream of new materials from carbon nanotubes has largely been unfulfilled due to the high cost of producing the carbon nanotubes. This same high cost situation currently exists with graphene. The original discovery of graphene utilized the sticky tape method. This method obviously can only be used for research purposes. A second method involves the epitaxial growth of SiC followed by thermal treatment to produce a layer of graphene. Chemical vapor deposition has also been shown to grow graphene on copper substrates. A wet chemical method of producing graphene involves the strong oxidation of graphite to produce graphene oxide followed by strong chemical reduction. The most promising known process is the graphene oxide; however, it begins with an expensive starting material. Another route to nanostructured materials and graphene is a method involving pyrolysis of polymers. In a slightly different approach to the exfoliation of graphite, supercritical fluids are utilized to accomplish exfoliation. A method for producing dispersions of graphite, graphite oxide and some graphene has been reported by utilizing ultrasound and surfactants. All of these processes are expensive and difficult to scale up to industrial scale.
Two of the critical properties of graphene are its strength and high surface area. If graphene can be fully exfoliated in polymers, the resulting nanocomposite may exhibit extraordinary strength. It may also potentially impart high electrical and thermal conductivity. There have been a number of patents reportedly utilizing graphene to make such nanocomposites. These composites, however, have not produced extraordinary property improvements.